This research study is designed to assess the trafficking pattern of autologous monocytes when given to humans intravenously. Monocytes will be removed from normal volunteers or cancer patients by cytapheresis and purified by counter current centrifugal elutriation (CCE). The purified monocytes will either be left at 4 degree (normal monocytes) for 4 hours or be exposed to clinical-grade recombinant gamma interferon activation; the cells will be labelled with lllindium and infused intravenously back into the normal donor or patient. Normal donors or cancer patients will first be given an intravenous infusion of autologous normal monocytes; if no untoward reactions are noted, the donors or patients may receive infusions of autologous-activated monocytes four weeks later. Frequent blood samples will be withdrawn from the patient or donor over the ensuing 96 hours to determine the rate at which the infused cells equilibrate with the marginating pool of blood monocytes (if one exists), and to determine the rate at which these cells emmigrate from the blood stream to enter the reticuloendothelial system and other tissues. In addition, multiple regional scintagraphs will be obtained to determine if these labelled monocytes preferentially localize to any one organ system. This information will be utilized to help us more rationally design adoptive immunotherapy trials in which purified autologous cytotoxic blood monocytes will be given to cancer patients intravenously.